Telephone system



.J. F. TOOMEY ET AL TELEPHONE SYSTEM- sept. 15, 1925. v 1,553,489

Original Filed Dec. 17. 1920 2 Sheets-Sheet 1 wwwtou flliie a Sept. 15,192s. 1553, 189

J. F. TOOMEY ET AL TELEPHONE sYsTEu' Original Filed Dec. 17, 1920 2Sheets-Shed! 2 Patented Sept. 15, 1 925.

unian 1,553,489 PATENT OFFICE.

.oelwtternq m em. raLnG ArHoQ Pe YrA n QRA IQN or NEW roar- TEIaEB QSYSTEM- App1ication filedDecem-berli, '1920, Seria1 No. 431,426. RenewedMarch 18, 1925. p

To all whom it mag -concern:

Be it known that we, J HN'F; TOOMEY and :HEN-R'Y E. Pr nnrs, residingatN'ewfiYor-k, in the county of New Y-o-rk and State of New York,respectively, have invented certain Improvements in Telephone Systems,.of which the 'follo wing is aspeci fication.

This invention relates to telepho1 1e exchange systems, and-moreparticularly to such systems in which connections -;are-esta b.- lishedbetween telephone linesterminating at diiierent switchboards.

O-ne of the objects of thein-vention is to provide a trunk circuit forsuclrsystems which is adapted to connectan. office of the manual typewith an ofiiceofeitherimanual or automatic type.

Another \ob'ect ot the invention is. to-providesuch system withapparatus at the orig inating end which, -in'case .the operator thereatdisconnects, will. maintain it in busy conditionuntil the remainder ofthecircuit is restored to normal.

A further object .oi'. theinuention ,isto provide signalingarrangementswhereby the operatorat the interconnecting .ofiicey-is. signaled uponthe. disconnectioniot' the originatin-gend irrespective. ot thecondition of the circuit at the opposite end.

These objeots,-.as well as other objects .ot the invention,- may beattained by means ,of the apparatus set torth in the followingdescription and illustrated; inthe: accompany.- ing drawings inWl1lCl1'F1gL1I'6S;1, 2 and 3 illustrate a circuit diagram of -.o ne-vembodiment of the invention. I Referring to the drawing, A represents aportionofan .operatofis toll cord which terminates inplug P. The plug Pis, adapted to cooperate with jack J whichlis connected to a trunkaC:atan interconnecting,-ortair dem oilice. .The trunk C terminates inplug P which: is adapted to co-operatewith the ack J of trunln'D in anoflice where connec tions areestablished manually, or jack J 2 of trunkE in an ofiice where connections are established by neans ofautomatic;-machinery. .=Both of the r=l2l tt-8I' trunks ,are adapted tobe comiected to-extensjion lines, such as subscribers. stations.

Ringing'key K isasso'ciated with the plug P .of-cord A for operating,electro1necha nism in the trunk G upon the connection of said plug withack J, and said trunk is pro- Vided with a key K forconnecting anoperatorsset therewith. The trunk C isequipped witlra. dial D in orderthat the operator may establish aconnection with a subscriber by means.01. the switching machinery which is shown diagrammatically at E. v

The idetailsof this circuit may now ficiently understood from. the afollowing ;de'-. scription of its operation.

Assuming that an operator at a tolloffice desires to establishaconnection witha subscriber, as, for example, alsubscriber whose lineterminates in a manual ofi ice at a jack 5 01 with asubscriber whoselinetermiates in an oliice where switchi-ngmachinery 1S. employed suchas shown at E, the toll operator will insert-plug P of CO-ldAllLjflCk Jand close the followingcircuiti' from battery,.sl eeize. contacts ofplug P and jackgJ, back contact of relay 5, conductordl), winding ofrelay 1 11," to. ground. This circuit .en;- erg izes relay 11, whichuponoperating closes acircuit through its trontcontact from bat.- tery,normal contactlofurelay '12, winding of slowreleasing relay 13 toground. :Relay13 as operated by the closing of this circuit, butperforms no useful function at this time.

The insertion of plug P.in .jack Jalso es tabhshes abridge- .across thetip andring conductors of the cord A by thetollowing current path:trom'battery, left-hand wind- 111g .of relay 14, conductor l5,;lettrhand normal contact of relay'l6, lett-hand back contact of relay17, conductor 18, ring contacts of jack .J and plug P, winding of super-Visory relay 19 of cord A, including'normal contacts-ofkey' K, tipcontacts =01 plug? andjack J, conductor 20, right-hand back contacts ofrelay: 17, right hand normal contact oif relay 16, right-hand windingotrelay lfieto ground. Ilheclosing of this circuit energizes relayli andsupervisory relay 19', butthe latter relay releases immediately upontheoperation of relay=16,-as will be described later,vand the supervisorylamp 21 doesenot light at this time. The operation of relay 1 1 closes acircuit through its frontcontact from ground, conductors 22 and 23, leftmiddle contact of relay 24,,conductor 25, lower back contactofrelay -26,filament of :lamp 27 to battery. The closing of this be sut.circu-itcauses the illuminaton of guard lamp tion by a holding circuitfrom battery, lefthand winding of said relay, conductor 15, left frontcontact of relay 16 to ground.

Vhen the operator at 0 notes the lighting of guard lamp 27, she operatestalking key K toanswer the call, and receives the num her of the desiredparty in the usual manner. The operation of key K closes a circuit fromground, through the lower contact of said key, winding of relay 24, 'tobattery, thus energizing relay 24, which breaks its left-hand middlecontact, and opens the circuit previously traced in connection with thelighting of lamp 27, thereby extinguishing said lamp temporarily. Theenergization of relay 24 maintains relay 16 in operated condition by aholding circuit from battery, outer left-hand contact of relay 24, conductor 30, normal contact of relay 29, right hand winding of relay 16,normal contact of relay '28, front contact of relay 14 to ground.

The operator at C after manipulating key K and ascertaining that thecall is for a party whose line. terminates at a manual office, as, forinstance, in jack J goes in on a call circuit in the customary manner,and receives a trunk assignment such as the trunk D, which terminates injack J The operator then restores key K to normal thereby deenergizingrelay 24 and causing guard lamp 27 to again glow. She then inserts plugP in jack J which closes a circuit from battery, winding of relay 34,conductor 36, sleeve contacts of plug P and jack J to ground. Thiscircuit energizes relay 34 and closes a circuit from battery,frontcontact of relay 34, conductor 87, winding of relay 26 to ground,thereby operating the latter relay. The operation of relay 34 opens itsback contact and thereby deenergizes relay 32, and the operation ofrelay 26 causes the guard lamp 27 to be ext-inguished by opening thecircuit previously traced through the lower-back contact of said relay;The insertion of plug P in jack J also closes a circuit from battery,left-hand winding'of relay 37 of trunk D, upper normal contact of relay38, conductor 39, ring contacts of ack J and plug P lowerno-rmalcontacts of relays 40 and 41, ring conductor trunk C, conductor 44,normal contact 62 of relay 43, conductor 42, winding of polar relay 31,tip conductor of trunk 0, upper normal contacts of relays 41 and 40,upper closed contacts of relay 26, tip contacts of plug P and jack Jconductor 45, lower normal contact of relay 38, right hand winding ofrelay 37 to ground. The closing of this circuit operates relay 37oftrunk D. The polar relay 31 does not operate at this time becauserelay 38 operates immediately, as will presently be described, and opensthe above traced circuit. 6 The operation of relay 37 closes a circuitthrough its front contact from ground, conductor 46, upper winding ofrelay 38, conductor 47, lower back contact of relay 48, filament of lamp49 to battery. This circuit operates relay 38 and also causes theillumination of guard lamp 49. Relay 38 at its back contacts opens thecircuit just described through the windingof polar relay 31, and atritsupper make contact closes a holding circuit for relay 37 from ground,make contact of relay 38 left-hand winding of relay 37 to battery.

The operator at the local oifice after assign ing the trunk, insertsplug P in jack J of the subscribers line, thereby. closing a circuitfrom battery, winding of relay 48, sleeve contacts of plug P and ackJ toground. This circuit operates relay 48 which breaks its lower backcontact and extinguishes lamp 49. At the same time it opens thepreviously traced circuit through the upper winding of relay 38, whichreleases said relay and thereby re-establishes the previously tracedcircuit through thepolar relay 31, whichnow operates, and opens thecircuitv through right-hand winding of relay 16. This releases relay 16and re-establishes the circuit traced above through supervisory relay 19in the cord circuit A, and relay 19 operates and lights supervisory lamp21 in an obvious manner. Thisprovides a ringing sig nal for the tolloperator A, who now operates the ringing key K of cord A whch causesringing current to be transmitted over the tip and ring conductors ofthe cord A, op-

crating relay 50 in the trunk C. The operation of relay 50 closes acircuit through its contact from ground, conductor 51, winding of relay41, to battery. This circuit operates relay 41, which connects ringingcurrent from source 52 over the front contacts of relay 41, tip and ringconductors of plug P and ack J in a well understood manner, therebyoperating relay 53 of trunk D. The operation of relay 50 also closes acircuit through its contact from ground, conductor 71, left-hand Windingof relay 16 to battery and operates relay 16 and closes the holdingcircuit for relay 14, as traced above, and maintains relay 14 inoperated condition. The operation of relay 53. closes a circuit throughits contact, conductor 54, winding relay 38 to battery. This circuitserves to again operate relay 38, which niaintainsrelay 3? in anoperated condition over the holding circuit previously traced and alsooperates relay which attracts its armatures and transmits ringingcurrent from source'57 over the tip and ring contacts of plug P and jackJ signals the subscriber in the usual manner. The toll operator atA'having signaled the subscriber, restores key K to normal therebyreleasing relay 50, which will in turn break the: energizing circuit forrelay 41 causing it to release. The release of relay 41 will disconnectthe-ringing current from the trunk and deenergiae relay and accordinglybreak the circuit by which relay 55 was operated. The release of "relay50 also releases relay116 by opening the'circuit through the left-handwinding of the latter relay. The release of relay 53 will deenergizerelay 38 bypopern ing the circuit through its lower winding.

The subscriber in response to the signal, will remove the receiver fromits book,

' thereby closing a circuit from battery, windof relay 58, upper backcontact of relay 55, tip contacts of plug P and jack J throughsubscribers station and return by way of the ring contacts'of said plugand jack upper contact of relay 4L8, lower back contact of relay 55 toground. This circuit will operate relay 58'and close a circuit frombattery, lower winding of relay 38, conductor 59 contact of relay "58,upper winding of relay 38, conductor 46, contact of relay 37 to ground.This circuit provides for the energization of relay '38, which inoperating will hold relay 3? energized by a circuit from ground, upperfront cont-act l relay 38, left-hand winding of relay 37 to battery.

The operation of relay 38 opens the circuit previously traced wherebypolar relay 31 of trunk C was operated, causing-said relay to release.The release of relay 31 will cause relay 16 to again operate by thecompletion of the circuit throughthe normal contact of relay 31,previously described. The operation of relay 16 will break its normalcontacts thereby opening the circuit formerly traced avhereby thesupervisory lamp 21'at cord A was illuminated. If the subscriber whoseline terminates at fja'ck J moves the switch hook up and down, relay 19alternately operates and releases"tliereby causing-supervisory lamp 21to flash.

VVhenthe subscriber vat the'terminati'on of a call hangs up thereceiver, the circuit whereby relay 58 was energized will be broken atthe subscribers switchhook, in ,a manner well understood 1 and relay 58will becbmedeenergized thereby opening the cir cuit by which relay '38was operated, causing said relayto release. The release or .,1"elay38will again provide for the operation v p I a w ground. Th1s"c1rcu1toperates relay "3% of polar relay 3lover normal contacts er relay 38 andtip' andiring conductors ofithe trunks D and C, energizing .relay 31 waspreviously out-lined. The operation not polar relay 31 of trunkC:opensrth'e circuit just described whereby relay 1-16 was .energize'd,thus releasingthe latter relay which causes the operation of relay 19 inthe cord A by a circuit previously traced. Theclosing ofthis circuitwill cause lamp 21 to glow which .givesthe operator at A 'a .dis connectsignal and she thereupon removes plug P'from jack J releasing relay l4..:Release: of relay 14 closes a circuit't hrough its back contact fromground, conductor 63, lower closed contact'of relay 26, fliil'azment oflamp '27 to battery. fThe olosing olthis circuit lights lamp 27 andthereby furnishes a disconnect'si'gnal for the -operator at O.

The release of relay 14 also cau'ses'the opertact and winding of-relay-60, conductor 61,

back contact of relay 14' to-groun d. The operation of relay 60 throughits left-hand front contact also closes'a circuit'flfor operating relay4L3, from ground-winding of relay-43 to battery. The operation of-rela'y43 will break at its left-hand contact 62, bridged circuit through polarrelay 31 thereby deenergizin-gthe latter 'relay and opening the circuitpreviously described whereby relay '37 of trunk D was energized.

The deenergization of relay-3'7 closes 'a: crr cuit through its backcontact from ground. through lower closed contact ol relay -48, filamentof lamp 49to battery, thus'causing lamp 49 to glow andrthis'serves asia' 'disconnectsignal for the operator at D. fTheop- 'erators at C andDupon-recei ing simul,

taneous disconnect signals, indicated-by the glow of lampsQTand 49, willremov'ethe plugs of their trunks 'lromwtheir associated Jacks andthe-circuit will be restoredtonorinal.

Ifthe tandem operator at C in response to a 'call, as indicated by theglowing "of guard lamp 27, .operates'key K and ascertains that the callisfor. a subscriber whose line terminates at an office such as indicatedat E, where switching machinery is used for establishing connections theplug 'P isinserted in ack J an'd the dial 'D of trunk'Gis operated in awellknow1rmanner to-set'lup-a connection by means of the selectorswitches Sand S at o'ffice E'. "The insertion 'o'fjplug 1 P? in: jack Jwill close alcircuit from batte y, f winding of relay '34s, conductor36, sleeve contacts ofyplug Pf :andqack l' -to i,

which closes a circuit through its front contact from battery, conductor87, winding of relay 26 to ground, thereby operating relay 26. Theoperation of relay 26 connects the tip strand of plug P to the tipconductor of the trunk C and also opens at its lower back contact thecircuit by which lamp 27 was lighted, it being understood that therelays 14 and 16 are energized as previously described in connectionwith the call to a manual office. The operation of the key K will closea circuit through its lower contact from ground, conductor 35, windingof relay 24 to battery. The operation of relay 24 closes the circuitpreviously traced for maintaining relay 16 in operated condition, andalso closes a circuit through its right hand contact from ground, overconductors 64 and 65, winding of relay 40 to battery when the dial Disoperated. The closing of this circuit will energize relay 40 andconnect the conductors 66 of dial D with the tip and ring conductors ofplug P and jack J The operation of dial D will step the automaticapparatus at trunk E to the proper subscribers line. As soon as theoperator at C has completed dialing, the circuit of relay 40 is openedat the off normal contacts of the dial. The operator at O, havingcompleted the dialing operations, restores key K ,thereby deenergizingrelay 24. In response to the dialing operations, the sleeve terminal ofswitch S will be connected with the sleeve contact of the subscribersline and will close a circuit from battery, through the sleeve contactsof switch S winding of relay to ground, thereby energizing relay 70. Theinsertion of plug P in jack J will not cause polar relay 31 of trunk Bto operate but when the final selector has seized the subscribers lineand relay 7 O is operated as just outlined, there will be a reversal ofcurrent which will cause said polar relay 31 to operate upon the closingof the following circuit: from ground and battery at trunk E, frontcontacts of relay 70, back contacts of relay 69, conductors 67 and 68,tip and ring contacts of jack J 2 and plug P tip and ring conductors oftrunk C, including the closed contact of relay 26 and back contacts ofrelays 40 and 41, winding of relay 31, conductors 42 and 44, and contact62 of relay 43. The operation of polar relay 31 causes thedeenergization of relay 16, which again completes the bridged connectionover its back contacts to the tip and ring conductors of cord A by acircuit'from ground and battery at relay 14 as formerly described,thereby energizing relay 19 of cord A and causing lamp 21 toglow, thusproviding a ringing signal for the operator at the toll'oflice A. Theoperator at A, upon receiving the ringing signal as indi! cated by theglowing of lamp 21, will op eratekey K of her cord and transmit ringingcurrent over the tip and ring conductors of said cord through thewinding of relay 50 thereby operating it. relay 5O completes a circuitthrough its contact from ground, conductor 51, winding of relay 41, tobattery, thus energizing relay 41. The operation of the ringing relay 50also operates relay 16 which in turn holds relay l4 operated. Theoperation of relay 41 causes ringing current to be applied in awell-known manner from source 52, over the tip and ring contacts of plugP and jack J switches SS and S 8 over the sub scribers line therebysignaling said subscriber. The removal of the receiver from its hook atthe subscribers station in response to signal will complete a circuitfrom battery, left-hand winding of relay 69, conductor 73, ring contactS through the subscribers station and return in the usual manner, tipcontact of switch S conductor 72, right-hand winding of relay 69 toground. This circuit will cause the relay 69 to operate, thereby openingthe circuit previously outlinedwhereby polar relay 31 of trunk C wasenergized thereby causing relay 31 to release. The deenergization ofrelay 81 closes a circuit through its back contact from battery,conductor 30, normal contact of re lay 29, right-hand winding of relay16, con tact of relay 28, front contact of relay 14 to ground. Thiscircuit operates relay 16 and opens the bridged circuit across the tipand ring conductors of trunk l3 and cord A whereby the lamp 21 wasilluminated upon the energization of relay 19.

When the subscriber whose line terminates at trunk E restores thereceiver to its hook, the circuit which was previously described fo-renergizing relay 69 will be broken and said relay will release therebyenergizing relay 31 of trunk C, which in turn causes relay 16 torelease. The relay 19 in cord A is energized by a circuit pre viouslydescribed in conneottion with a call to a manual office and theoperation of said relay causes lamp 21 to glow, thereby giv Theoperation of.

ing a disconnect signal to the toll opera- 7 disconnect before thesubscriber who is connected with either the manual or automaticmachinery controlled oflice hangs up, theremoval of plug P from jack Jwill cause relay relay 11 will close a circuit from battery normalcontact of relay 12-, back contact; oi:

relayll, make contact of relay 13, this re-v lay being momentarily heldoperated as it is slow to release, conductor 77, througlrthe windingsofrelays 76. and 5 in series to ground. This. circuit, will cause theopera-r tion: of relay. 76 and differential: relay 5. The operation otthe latter relay .will complete a lockingcircuit from ground, through.its, right-hand winding, and make contact, conductor. 78,;normal contactof relay '13, this relay now being. released, back contact of relay 11,norinal contact of relay 12, to, battery. The outgoing end ot trunkCterminating. in jack J will then automatically lock. itself and testbusy until said, trunk. is disconnected at its opposite end. Should theoperator at A insert. plug P in jack J again at this time, thedifferential relay 5 would be released and, the circuitrestored. to thesame condition as was. previously out.. lined upon theoriginalassociation of, said plug and; jack. However, it the operator atA doesnot come in on the circiiit again, theoperator at C will receive adisconnect, signal in the following. manner: The relay 76 being operatedas; previously indicated will close a; circuit through its. left: handfront contact from the battery, right hand outer contact of, relay 5,ring conduce tcr of trunk C, conductor 18, lett-.-hand normal contact ofrelay 1.7, conductor 7 9, wind mg of relay 80, conductor 81, right-handmake contact. of relay 16, .right-hand back contact of. relay 17conductor 20, tip conductor trunk C, conductor 82, right-hand makecontact of relay 7 6. to ground. This circuit energ zes; relay 80,which, 1n turn, closes a clrcuit .from ground, through lts.

contact. windingo't relay-2S to battery, en,-.

ergizing relay 28. The operation of relay 28opens its contact andbreakst-he holding.

. circuit previously described through right-hand winding of relay 16,causing this relay to'release. The deenergigzation of res lay 16 opensits left-hand front contact and causes relay 14 to be released in anobvious manner. The release of relay 14 com-. pletes a circuit throughitsback contact from ground, conductor 63, lower.malre contactof relay26, filament of relay 27, to battery. This circuit causesthe lightingof; guard lamp 27, which serves asa disc-on; nect signal for theoperator at C. The releaseof relay lt also closes a circuit, through.its k C t r m. re ade W nding. i l y 2 ondu o midd kec ntact of relay 26 to battery. This: circuit energizes relay29 The-operator at Q,response to'the disconnectsignal, will with draw plug: P from its.associated jack, thereby causing the release of relay 12 6, whish 'Qlees a; ei er t thr u h middle ack ontact fr m battery, cenductor. 84,.winding. of; relay, 17, conductor 85, right. hand closed contact ofrelay 29 to ground. Relay; 2%; being sloW-to-release, is. momen-.tarilyheld operated, Relay 17 is energized, nenfil'wdc ing othiscir t,d, a rela.y..,7 6=' atA; and relays. 80 and 28 of! trunk; hm br his timee ea ed, he f llowing circuit will. he established: from battery, leftwinding.ot'relay'l hconductor 15, back contactjrelay 16,; left frontcontact relay 17 conductcr 2Q, tip conductor of trunk 0,, ond c r .2,.ght ne mal n aa f. elay 7 6, winding ofypolar-relay 83, left normalcontact of relay 7,6 outer-closed contact of: relay 5, ring, conductorottrunk; G, con-v ductor 18, right front, contact of relay 17 ack. sen-tct: f ay 5. right-h n Wind. ing; t, relay. 14; to, ground. This. circuitreverses current through. polar relay 83 n au est 0 Qp et Th ep e ie ofthe polar relay 83 completes. acirI-z Quit. thr ugh its ro nd d c n a o;b tery. through, the. winding of relay. 12, a si he latt relay e p r a win. turn, breaks itsnormal contact and opens. the lqcking. circuitpreviously re-v ferred t0, whereby. rel y .2 was held energized, It willbe mderstood, that after a certaintime slowrelease. relay 29 will be?come deenergized, thereby releasing relay. 17 andthe latter, in turn,releasing polar,

relay 83,,thus restoring the circuit to norma a s w z h pera r t A. d eent insert 1 1551151 i c 'l n th n remove said plug. theretrornf, thecircuit will func. t ns milarly o that described in connec-. tion withremoval :of the; plug before the subscriber, has returned jthe receiverto itsv hook, 1 Inthi's case, however, the slow release relay32; willgbemomentarily held up after the release Jot relay 14: and relay 29-Will beenergized by circuit from ground, baclr contact of relay 14,;winding of;relay 29, closed contact relay 32,- conductors. 89 and 84 .tbatteryhyWay. of middle back contact of relay 26. The. operation ofrelay- 29 re.-. sults in the. operation of polar. relay 8 3 and theclear-ingot the circuit. in thesame manner as just described, in thecase of: a dis;

connect, Relay 32wi11, after-a time, release a d r ak. he on act w r bythe i1 y- 2 1- n a elephan sy m. omp i g a t ll. stir ten er; vita sihse bees l manually operated trunks and automatically operated trunksforassociating said sub-' scribers lines and said tandem oflice, a trunkcircuit at the tandem ofiice for interconnecting said toll oflice withsaid manually operated trunks and with said automatically operatedtrunks, means including a polar relay bridged across the trunkcircuitand responsive to its connection with said manually operated trunk andwith said automatically operated trunk for signaling said toll oflice,means at said toll oilice for impressing current on said trunk circuit,and means associated with said trunk circuit responsive to theapplication of current thereto for impressing current on said manuallyoperatedtrunk and said automatically operated trunk whereby thesubscribers on the lines connected with the two latter trunks aresignalled;

2 In a telephone system comprising a toll office, a tandem oflice,subscribers lines, manually operated trunks and automatically operatedtrunks for associating said subscribers. lines and? said tandem oifice,a. trunk circuit at the tandem office for interconnecting said tolloiiice with said manually operated trunks and with said, automaticallyoperated trunks, means including apolar relay bridged across the trunkcircuit and responsive to its connection with said manually operatedtrunk and with said automatically operated trunk for signaling said tolloflice, means at said toll ofiicefor impressing current on said trunkcircuit,

means associated with said trunk circuit, responsive to the applicationof current thereto for impressing current on said manually operatedtrunkandsaid automatically operated trunk whereby the subscribers onvthelines connected with the two latter trunks are signalled, and meansbridged across said trunk circuit and responsive to the disconnection ofthe toll ofiice therefrom for operating a disconnect signal associatedwith said trunk circuit.

3. In a telephone system comprisinga toll ofiice having toll cords,signaling means associated therewith, a tandem ofi ice, subscribersstations manu ally operated trunks and automatically operated trunksassociating said'subsc'ribers stations with saidtandem oflice, trunkcircuits at said tandem of fice for-interconnecting said toll cordswithsaid'manually operated trunks and with said automatically "operatedtrunks, signaling means associatedwith said trunk circuits, meansincluding "a ,polar relay bridged across each trunk circuit 7 andresponsive to the connection of said trunk circuits and said manuallyoperated trunks and with said automatically operated trunks lforoperating the signaling means in said toll cords, means associated withsaid toll cords for impressing current'on said trunk circuits,

means associated with the trunk circuits responsive to the applicationof current thereto for impressing current on said manually operatedtrunks and on said automatically operated trunks whereby the subscribersstations connected with the two latter trunks are signalled, meansassociated with said manually operated trunks and with saidautomatically operated trunks for operating the signaling meansassociated with said toll cords as a disconnect signal upon thedisconnection ,of the subscribers stations, and means bridged acrosssaid trunk circuit responsive to the disconnection of the toll cordstherefrom for operating the signaling means of said trunk circuits.

4. A. telephone system comprising a toll office, signaling meanstherea-t, a tandem oi'lice, signaling vmeans therea-t, subscriberslines, manually operable tandem trunks and automatically operable tandemtrunks associating said subscribersilines with said tandem Office, atrunk circuit interconnecting said toll oiiice and said tandem ofiice, acircuit bIIClgGdiLCIOSS' said trunk, said circuit controlling said tolloffice signaling means,

a. relay controlling said bridged circuit, a polarized relay associatedwith saidtrunk controlling said first relay, a third relay i11 cluded insaid bridged circuit and controlling said tandem oftice signaling means,and means in said tandem trunks controlled by said subscribers lines forcontrolling said polarized relay whereby said toll oliice signalingmeans may be controlled. Y 7 y 5. A telephone system comprising a tollolfice,a toll cord includingsignaling means located thereat, a tandemofiice, subscribers lines, manually operable'tandem trunks andautomatically operable tandem trunks associating said subscribers lineswith said tandem ofiice, a trunk circuit interconnecting said tollottice and said tandem oflice, signaling means in said trunk at saidtandem otfice, a circuit bridgedacross said trunk, said circuitcontrolling saidtoll o-ffice signaling means, a relay controlling saidbridge circuit, a polarized relay associated wit'hsaid trunlrcon:trolling said first relay, a third relay included in said bridgedcircuit and controlling said tandem oiiice signaling means, means insaid tandem trunks controlled by said subscribers lines foricontrollingsaid polarized re,- lay whereby said toll office signaling means may becontrolled, said third relay being locked up over a contact of saidfirst relay and the tandem otfice signaling means being thusextinguished when a connection is establ shed between said toll cordand; a subscribers llnesand means associated with said trunk andoperable when said tool, cord is third relay causes said tandem officesi m means to function again.

6; A telephone system comprising a toll office, a toll cord includingsignaling means located thereat, a tandem oflice, subscribers lines,manually operable tandem trunks and automatically operable tandem trunksassociating .said subscribers lines with said tandem otfice', a trunkcircuit interconnecting said toll office and said tandem of: fice,signaling means in said trunk at said tandem ofiice, a circuit bridgedacross said trunk, said circuit controlling said toll ofiice signaling.means, a relay control ling said bridged circuit, a polarizedf relayassociated with said trunk controlling said first relay, a third relayincluded in said bridged circuit and controlling said tandem officesignaling means, means in-said' tandem trunk controlled by saidsubscribersllines for controlling said polarized re lay, whereby saidtoll office signaling means may be controlled, said third relay beinglocked up over a contact of said first relay and the tandem officesignaling means being thus extinguished when a connection is establishedbetween said tollcord and a subscribers line, means associated with saidtrunk and operable when said toll cord is disconnected from said trunkbefore said connect-ion hasbeen terminated by said sub:

scriber for releasing said first relay and breaking said lockingcircuitwhereby said thirdrelay causes said tandem ofiice signal.- ingmeans to function again, and means associated with said trunk andoperable upon the diseonnectionof said trunk from one of said tandemtrunks' afte-r said toll cord hasbeen disconnected from said trunk forrestoringalllot'said apparatus to normal.

7. In a telephone system comprising a. toll office, a tandem otfice,subscribers lines, manually operated trunks and automatically operatedtrunks for associating said subscribers lines and said tandem office",switches associated with the automatically operated trunks, a trunklcircuitgatl the tandem office for interconnecting said toll office withsaid manually operated trunks and with said automatically operatedtrunks, a dial associated with the trunk circuit for operating saidswitches, means bridged across the trunk circuit and responsive to itsconnection with said manually operated trunk and with said automaticallyoperated trunk for signaling said toll office, means at said toll officefor impressing current on said trunk circuit, and means associated withsaid trunk circuit responsive to the application of current thereto forimpressing said current on said manually operated trunk and saidautomatically operated trunk, whereby the subscribers on the linesconnected with the two latter trunks are signaled.

8. In a telephone system comprising a toll office, a tandem office,-subscribers lines,- manually operated :trunks and automatically i op--era te'd trunlrsfor associating said subscrib= ers' lines and saidtandem ofiice, atrunk circuit at the tandem ofiice for inter-connectingsaid toll oflice with said-manually operated trunks" and withs-aidautomatically operated trunks, means bridged across the trunk circuitandresponsive-to its connection with said manually operated trunk andwithsaid automatically operated trunk tor'signaling s aid toll ofiice,means at said toll office for impressing current on said trunk circuit,means associated with said trunk circuit responsii e tothe applicationof current thereto for impressing current on said manuallyoperated"trunk and said automatically operated trunk, whereby thesubscrio erson'the lines connected with; thetwo' latt'er trunks. are signaled, andmeans associated'with said trunk circuit and responsive to thedisconnection of the toll o'flice therefromand' the opening ot asubscribers line-tor simultaneously operating a di onnects mi insaidmeantime and in said ina-n' ually operated-trunk i '1 9 In atelephone system comprising a toll office having toll, cords,signaling-means associated therewith, a tandem office, sub scribersstations, manually operated trunks and. automaticallyoperated trunks forasso c'iatiiig said subscribers stations with said tandem office,trunkcircuitsj'at said tandem oiiice .for inter-connecting said toll"cords with said manually; operated 'trunks and with said automaticallyoperated trunks;

signaling means associated with said tr'ui'ik circuits, ineanS...including a polar relay bridged .across each trunk-circuit andresponsive to the connection orsndn-uak-cie cuits and-saidiiianually'operated trunks and with said ai'itomatically operated trunksfor operating thesig naling means in said toll cords, meansassociated'with said toll cords for impressing currenton -said trunkcircuits, means associated with the trunk-circuits responsive to theapplication of 'currentth'ereto torimpressing current on said manuallyoperated trunks and said automatically operated trunks, whereby thesubscribers stations connected with the two latter trunks are signaled,means associated with said manually operated trunks and with saidautomatically operated trunks for operating the signaling meansassociated with said toll cords as a disconnect signal upon thedisconnection of the subscribers stations, and means bridged across saidtrunk circuit responsive to the disconnection of the toll cordstherefrom and the disconnection of the subscribers stations forsimultaneously operating the signaling means of said trunk circuits andsaid manually operated trunks.

10.-In a telephone system comprising a too V toll ofiice having tollcords, a tandem office,

subscribers lines, manually operated trunks and automatically operatedtrunks for associating said subscribers lines and said tandem office,switches associated with the automatically operated trunks, a trunkcircuit at the tandem office for inter-connecting said toll ofice withsaid manually operated trunks and with said automatically operatedtrunks, a dial associated with the trunk circuit for operating saidswitches, means bridged across the trunk circuit and responsive to itsconnection with said manually operated trunk and with said automaticallyoperated trunk for signaling said toll office, means at said toll officefor impressing current on said trunk circuit, means associated with saidtrunk circuit responsive to the application of current thereto forimpressing said current on said manually operated trunk and saldautomatically operated trunk, whereby the subscribers on the linesconnected with the two latter trunks aresignaled, and means associatedwith said trunk circuit for simultaneously operating a disconnect signalin said trunk circuit and said manually operated trunk upon the openingof the subscribers lines and the disconnection of the toll cord from thetrunk circuit. 7

11. In a telephone system comprising a toll office having toll cords, atandem office, subscribers lines, manually operated trunks andautomatically operated trunks for associating said subscribers I linesand said tandem office, switching apparatus associated with theautomatically operated trunks, a trunk circuit at the tandem office forinter-connecting said toll office with said manually operated trunks andwith said automatically operated trunks, a dial associated with the saidtrunk circuit for. operating said switching apparatus, means bridgedacross the trunk circuit and responsive to its connection with saidmanually operated trunk and with said automatically operated trunk forsignaling said toll office, means at said toll ofiice for impressingcurrent on said trunk circuit, means associated with said trunk circuitresponsive to the application of current thereto for impressing saidcurrent on said manually operated trunk and said automatically operatedtrunk whereby the subscribers on the lines connected with the two lattertrunks are sig-' naled, and means associated with said trunk circuit forsimultaneously operating a disconnect signal in said trunk circuit andre leasing said switching apparatus in. the automatically operatedtrunks upon the opening of the subscribers lines associated with thelatter trunks and the disconnection of the toll cords from the trunkcircuits.

12. In a telephone system comprising a toll office, a tandem office,subscribers lines, manually operated trunks and automatically operatedtrunks for associating said subscribers lines and said tandem office,atrunk circuit at the tandem officefor inter-connecting said toll officewith said manually operated trunks and with said automatically operatedtrunks, means bridged across the trunk circuit responsive to itsconnection with said manuallyoperated trunk and with said automaticallyoperated trunk for signaling said toll office, means at said toll officefor impressing current on said trunk circuit. means associated withsaid-trunk circuit responsive to the application of current thereto forimpressing current on said manually operated trunk and saidautomatically operated trunk, whereby the subscribers on the linesconnected with the two latter trunks are signaled, and means associatedwith said trunk circuit and responsive to the disconnection of the tolloffice therefrom for maintaining said trunk circuit in busy conditionuntil its disconnection from said manually operated trunk and saidautomatically operated trunk.

In testimony whereof, we have signed our names to this specificationthis 15th day of December 1920. i 7

JOHN F. .TOOMEY. HENRY E. PHELPS.

